Key Control

Various mechanisms are in existence to stop keys from being duplicated. The most common include "DNC" (Do not Copy) and Restricted Keyways that are generally protected by law.

Do Not Copy (DNC)
Many keys are stamped with "DNC" to deter duplication of the key, however many hardware stores, shops that provide a key cutting service and even some locksmiths will copy the keys, as there are no laws in place to prevent duplication. Do Not Copy keys are seen as more of a deterrent to stop people from getting the keys copied, but more recently it's become apparent that most places that provide key duplication will

Restricted Keyways
Many larger institutions employ use of Restricted Keyways to prevent key duplication. The plug and the key blanks are often protected by a patent to prevent blanks from being created, however some restricted keyways rely on "Security through Obscurity" in the hope that key blanks and plugs will not be manufactured by anyone else.

Most Locksmith associations such as the Master Locksmith Association of Australia (MLAA) provide it's members with access to restricted keyways and plugs, making key duplication without authorization difficult. However Restricted Keyways can be recreated through custom - created keys. Keys can be created using nothing but a Hacksaw blade and a tension wrench.

Key Cards
Often Restricted Keyways and even some DNC keys are protected by use of a "Key Card" (not to be confused with RFID smart card systems sometimes referred to as "Keycards") that is intended to be presented before a key can be duplicated.